When the Exchange Store Manager (ESM) service processes Dumpster Items it always associates/links those items to the "Deleted Items" folder.
Items are moved to the Dumpster as a result of deletion, such as;
Shift-Delete performed on an item in Outlook
Emptying the "Deleted Items" folder in Outlook
Archive Manager Delete Policy
Moving an item to a different mailbox such as a PST or a Public Folder
Microsoft significantly re-architected the Dumpster in Exchange 2010, preventing Archive Manager from determining which mailbox folder the deleted item should be associated with so all Dumpster items are associated with the "Deleted Items" folder.
Previous versions of Exchange have Dumpster 1.0, Exchange 2010 has Dumpster 2.0.
Fixed in versions of Archive Manager 4.5 and higher.
Disable Dumpster processing by following the resolution from this solution: SOL44554
For more information on the cause please see this article: http://msexchangeteam.com/archive/2009/09/25/452632.aspx